Transcript The Particle Nature of Light

The Particle Nature of Light
Key Concepts…
• Experimental:
– Black body radiation curve
– Discovery of Photoelectric Effect (Hertz,
Lenard, Millikan)
– Compton Scattering
• Theoretical
– Planck quantization of energy
– Einstein extends Planck’s ideas to the
“quantum” of light or photon
Photoelectric Effect is Critical
• Millikan’s brilliant
(albeit reluctant)
confirmation of
Einstein’s quantum
hypothesis
• Shows that light
behaves in a very
“non-classical” way
go to kcvs.ca applet of this
Photon reveals light’s “particle
nature”
• Light has both wave and particle nature
but is neither
• Photon is an example of the strange
quantum idea we will also call “quanton”
• First glimpse of the wave-particle duality
that lies at the heart of quantum physics
Compton Scattering…
• The scattering of xray photons by
electrons provides
compelling evidence
for the photon idea
go to kcvs.ca applet
Sample questions…
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Q3T.1, T4
Q3B.4
Q3S.1
Q3S.3
Q3S.7